Crease-proof woven and knitted fabrics



United States Patent 3,447 884 GREASE-PROOF W0"EN AND KNITTED FABRICSEugen Hasselkuss and Emil Kimmig, Freiburg im Breisgau,

Germany, assignors to Deutsche Rhodiaceta AG, Freiburg, im Breisgau,Germany N0 Drawing. Continuation-impart of application Ser. No. 349,133,Mar. 3, 1964. This application May 13, 1966, Ser. No. 549,824 Claimspriority, application Germany, Aug. 3, 1963, D 42,175; Aug. 13, 1963, D42,231 Int. Cl. D06c 15/00 US. Cl. 8-17 15 Claims ABSTRACT OF THEDISCLOSURE A process for finishing secondary cellulose acetate woven andknitted fabrics to impart wash and wear properties thereto comprisingembossing said fabric on at least one s1de at an elevated pressure andat a temperature of between about 80 to 150 C., washing, dry heating theembossed fabric at a temperature of between about 180 to 200 C. for fromabout 20 to 30 seconds, coloring, and steam fixing the embossed and dryheated fabric for from about 3 to minutes at a temperature of from about115 to 125 C., all steps in said process being conducted underconditions wherein the fabric is not stretched.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of application Ser. No. 349,133, filed Mar. 3,1964, now abandoned.

The present invention relates to crease-resistant woven and knittedfabrics, which retain their shape after wearing and washing. These wovenand knitted fabrics consist mainly of filaments or threads made fromsecondary cellulose acetate. They may also contain some amounts of metalthreads or textiles other than cellulose acetate, such as wool or nylon.Ready-made goods made of the fabrics of the invention are easily handledand have an appearance so satisfactory that they need no ironing and maybe reused immediately after washing and drying.

Up to now, woven and knitted fabrics of secondary cellulose acetateshowing the above mentioned properties have not been available. Variousfinishing processes have been described for rendering fabrics ofcellulose acetate threads or filaments and spun yarn essentiallycreaseproof. For this purpose resins have been used, but satisfactoryresults have not been obtained. A somewhat better effect has beenattained for woven fabrics in the manner wherein the fabric has beenbound by flotation, preembossed and finished without stretching. By thismethod too, it has not been possible to obtain fabrics of secondarycellulose acetate which need not be ironed after washing.

The object of the present invention is essentially creaseproof woven andknitted fabrics made of secondary cellulose acetate showing theproperties above described and methods of producing such fabrics.Further objects of the invention are apparent from the followingdetailed description.

It has been found that fabrics with a high degree of crease-proof andwash and wear properties can be obtained by using the following stepswith regard to the treatment of woven fabrics:

(a) The crude woven fabric is embossed on one or both sides, preferablyone, to obtain preferably a finely grained apearance or pattern. Thetemperature is maintained between about 80 and 150 C. and the pressureis elevated to from about 5 to 12 tons.

(b) The woven fabric is washed and desized by treatment with water,which may contain a small amount of synthetic detergent, at a moderatelyhot temperature of 3,447,884 Patented June 3, 1969 ice roughly 40 to 90C. and preferably at about to C. Depending on the size used (e.g., glueor starch size) temperatures as low as 40 C. are sufficient. The wateris separated from the fabric, preferably under subatmospheric pressure(vacuum) and not by pressing off, squeezing, or centrifuging. Thematerial subsequently is dried, e.g., by hot air without stretching.

(c) The woven fabric is heated for about 20 to 30 seconds, preferably byhot air, under free shrink conditions by, for example, passing it over astenter in slack condition (i.e., the web is fed faster than it iswithdrawn) to a temperature of between about 180 to 190 C.

(d) The so-treated woven fabric is, in a conventional manner, dyed orprinted and, if printed, normally steamed for stabilizing the color. Itcan then be washed and dried and finished with common finishing agents,and may then be re-dried with moderate steaming.

(e) The thus-treated woven fabric is fixed in the presence of steam fora period of about 3 to 5 minutes.

When knitted fabrics are to be treated according to the invention, steps(a) and (b) are reversed, i.e., step (b) is carried out before (a). Thepressure during the embossing step may be somewhat lower.

Step (a) as outlined above is conducted on conventional embossingmachines having a normal working width of between about to 200 cm.depending upon the width of the fabric treated. The broad temperatureutilized is maintained between 80 and 150 C. and preferably between andC. The elevated pressure utilized is substantially dependent upon theworking width of the particular embossing machine utilized and rangesbroadly from between about 5 to 12 tons with the preferred range beingbetween 7 and 11 tons. As the working width of the machine increases theelevated pressure also generally increases with the ranges being asfollows: 100 cm. working width, 5 to 10 tons with 7 to 8 preferred; cm.working width, 6 to 11 tons with 8 to 9 prefered and 200 cm. workingwidth, 7 to 12 tons with 9 to 10 preferred. As can be seen the elevatedpressures which can be utilized increase linearally as the Working widthincreases. Generally, the elevated pressure utilized is somewhat higherwith woven fabrics than with knitted.

The woven or knitted fabrics are embossed using standard embossingrolls. There is no industry standard by which such rolls are classified,the choice normally being made by visual inspection. The shape of thepattern on the embossing rolls is not critical and may be of any nature;geometric or non-geometric, square, triangular, irregular, etc. Thepattern itself is preferably finely grained but there is no upper limiton the coarseness of the pattern except practical considerations.Preferably the pattern will be sufliciently fine such that aftercompletion of all the process steps the pattern will be nearlyunrecognizable on the finished fabric. Needless to say, if desired forspecial effects, the embossing pattern may be so course as to leave areadily discernable pattern on the finished fabric.

The minimum fineness of the embossing pattern should of course be morethan totally smooth. Good results have been obtained with embossingpatterns having from about 400 to 17 peaks per square centimeter. Theeffect of step (a) is essentially to increase the final wash and wearproperties in the finished fabric and to impart dimensional stability(with respect to shrinkage) so as to minimize shrinkage in thesubsequent process steps. The step appears to stabilize the thread andto impart a slight, superficial hardening or corification to the thread.At the temperature specified and with elevated pressure, the coarsenessof the embossing pattern is at least sufficient to impart thedimensional stability above mentioned. This also insures the increase infinal wash and wear properties.

In line with the essential requirement that minimal stretching andtensile stress is applied to the fabric during the process steps it goeswithout saying that the embossing rolls turn at the same speed to avoidany stretch in the fabric. The fabric may be embossed on one or bothsides (i.e., one or both rollers may be engraved or patterned) andpreferably in the case of woven fabrics one side is embossed while withknitted fabrics it is possible to emboss on one, two or even on neitherside.

When utilizing a fine embossing pattern, the upper embossing roll isnormally heated and patterned while the lower roll is an unheated,unpatterned roll of, for example, rubber or cotton. Thus only one sideof the fabric is embossed during a single pass through the rolls. Withcoarse patterns, the lower roll usually bears a pattern correspondingwith the upper roll (though still unheated) and the fabric is embossedon both sides in a single pass through the rolls.

Step (1)) above is essentially a conventional washing and, wherenecessary, desizing operation (knitted fabrics are normally not sized).The washing is designed to remove impurities remaining from the weavingor knitting operation. The use of vacuum to remove the water insures nostretching of the fabric. When operating with woven fabrics, step (a)normally precedes step (b) while with knitted fabrics generally theopposite is true. The reason for this is that knitted fabrics tend toshrink more than woven fabrics (up to 10 percent during washing) and theshrinkage tends to minimize the effects of embossing in step (a). Assuch, with knitted fabrics step (b) may also be conducted before step(a) if desired, particularly where the woven fabric has a low mechanicalstability since after washing the threads are better able to stand thesubsequent embossing step.

While the general temperature range of step (c) is between about 180 C.and 190 C., a slight exceeding of this temperature is not detrimental.Generally the tempera? ture may range from 180 to 200 C. This thermalfixing of the woven or knitted fabrics is carried out in general bydry-heating the woven or knitted fabric being under slack condition. Forexample, the fabrics may be fed to a stenter (frame) in such a way thatthey do not undergo stretching even after fixing. This feeding underslack condition must be applied in both the longitudinal as well as thetransverse direction of the woven or knitted fabric.

The treatment of cellulose acetate at the high temperatures of about 180to about 190 C. or 200 C. has not been carried out up to now, asdetrimental effects upon the cellulose acetate substances have beenexpected. It is thu most surprising, that with such high temperaturesthe described advantageous properties of the woven and knitted fabricsof celluose acetate may be attained while avoiding any detrimentaleffects.

Step (d) is a conventional dyeing or printing step known per se in theart. Step ((1) normally follows step (c) particularly where a dyed orprinted pattern is to be imparted to the fabric. Furthermore since stepinvolves high temperatures, the dyestuffs may not be resistant to suchhigh heat and may be adversely effected. However, in the case of uniformdyeings or printings and where heat stable dyestuffs are used, step (d)may come before step (0) since shrinkage during step (c) will have noeffect on the colored fabric and the dyestuff will resist the high heat.With patterned fabric the shrinkage may not be uniform and the patternmay become distorted.

Step (e) is conducted by contacting the fabric with steam as dry aspossible for a period of about 3 to 5 minutes. If the fabric is treatedfor less than 3 minutes, some effect will be obtained but at less than1.5 minutes there is no worthwhile increase in the wash and wearproperties of the finished fabric. If the dry steam contact is longerthan 5 minutes the effect is obtained but the longer steaming does notimprove the effect and hence becomes uneconomical. The temperature ofthe steam during treatment is between about 115 and 125 C., e.g., 120 C.This step imparts the final dimensional stability to the fabric andimproves the wash and wear properties.

The temperatures above referred to are temperatures at which the fabricis treated during processing (e.g. to C. in step (e) refer to steamtemperature).

The new process gives to woven and knitted fabrics a smoother and morepleasant touch then with the process of copending concurrently filedpatent application Ser. No. 549,826 (a continuation-in-part of US. Ser.No. 274,329). This new process gives a further advantage as in the caseof knitted fabrics the embossing can be omitted entirely without greatlyaffecting the final result of the process. This improved process is ofspecial advantage in the case of knitted fabrics as embossing sometimesis connected with difficulties, e.g., by rolling of the edges of theknitted fabrics, thus causing conveying difiiculties in the finishingtreatment. Normally, with woven fabrics, embossing on only one side ispreferred. Where the woven fabric is heavy and thick embossing on bothsides is of advantage. Twill fabrics, e.g., and fabrics with knop yarnsmay be embossed only on the back side at an approximate temperature of90 C. to 100 C. in order to maintain their pattern. Similarly, wovenfabrics with tabby (calico) weave may be handled.

Tests have shown that if the above conditions are not maintained duringthe process steps, the improved wash and wear properties of the presentinvention will not be obtained. For example, tests wherein the embossingwas carried out at 30 C.; where the hot air treatment was deleted; whereall or some of the steps were conducted under substantial tensile stressand where embossing and/or the final dry steam treatment were deleted,all other process steps being the same, establish inferior wash and wearproperties resulting.

Except for this basic deviation, i.e., brief termal fixing at hightemperature in place of the dry steam treatment taught in the copendingapplication and the possibility of omitting the embossing stepcompletely, if desired, with knitted fabrics and with woven fabricspreferably embossing on one side only, the new process uses the sameprocess steps described in said patent application.

As in the case of the process of said patent application it is importantthat all the process steps are carried out without minimal stetching ofthe fabric in either length or width and with the application or minimaltensile stress to the fabric in any direction. It is further importantthat the fabric not be pressed (except of course during the embossingstep) and folded, but rather be flattened or spread out while beingtreated, since wrinkles or creases would otherwise be fixed in thetreated fabric. The entire process is conducted under slack conditionswhich allow free shrinkage.

After these process steps have been carried out, the fabric is ready fortailoring. It has been found that the retention of dimensions of thethus treated fabric is at least about i1%.

The properties of the thus treated woven or knitted fabrics areparticularly favorable if these consist of filaments with fibrils of lowcount gauge, e.g., filaments of 75 denier with 50 fibrils or denier with100 fibrils, and if their weave is loose, e.g., a flotation weave.

For the sake of a different appearance of the woven or knitted fabricstreated according to the invention, warp and/or weft filaments may beused having an irregular titre. This is illustrated by the following:

The filament leaving the spinning nozzle has a constant thickness if thefilament is subjected to a constant tension. In this manner the filamentis regularly reduced in thickness with regard to the diameter of thespinning nozzle. If the tension is periodically relaxed and increased,the fabric obtained from such filaments shows a regular pattern. Thefabrics used in the present process are made of filaments which whenwoven or knitted do not lead to an undesired regular pattern of thefabric, but to a linen like texture. Fabrils are used which have, e. g.,an average titre of 4 denier and have their changes in titre arranged atirregular intervals.

Beside the use of filaments with an irregular titre, the pattern of thewoven fabric may be advantageously infiuenced by using woven fabricswith a dense set and bound alternately by flotation and shortly tiedfilaments as, e.g., in the case of a twill weave.

By secondary acetate is obviously meant the partially hydrolyzed fullacetate which is acetone-soluble as opposed to the full acetate normallyreferred to as triacetate.

The following examples are not to be understood as a limitation of theinvention but only as an illustration.

EXAMPLE 1 A woven fabric is treated. The warp filaments are filaments ofsecondary cellulose acetate 75 denier with 50 individual fibrils and 190turns per meter. The weft filaments are filaments of secondary celluloseacetate of 150 denier with 75 individual fibrils and 80 turns per meter.The woven fabric is in the condition of a tabby weave, with very closeset, i.e., 73 filaments per cm. in the warp and 30 filaments per cm. inthe weft. The woven fabric is embossed on one side at 120 C. and at apressure of 9 tons on a 150 cm. working width machine with a finecrystal like pattern. Then, the woven fabric is wetted and desized inbook form up to a temperature of 75 to 80 C. using a bath containingsoap and ammonia. Thereafter, the liquid is drawn off by vacuum and thefabric dried on a short-loop-drier. The woven fabric is put withoutadditional stretching on a pinstenter and fixed at a temperature of 185to 190 C. for 25 to 30 seconds under slack condition. The fabric is thenprinted with dispersed dyestuffs, steamed in a star streamer, carefullyrinsed in conventional manner and dried on a short-loop-drier.Subsequently, the fabric is subjected to fixing with steam as dry aspossible for 4 minutes at 120 C. in a finish decatizing machine.Thereafter the fixed fabric is dried and passed without additionalstretching through a breaking machine for modifying the touch of thewoven fabric.

The same treatment may be applied to plain woven fabrics.

The woven fabric thus treated shows excellent wash and wear propertiesand a touch like natural silk.

EXAMPLE 2 The woven fabric shows a serge-weave. The filaments used forwarp are of secondary cellulose acetate 75 denier with 50 fibrils. Thefilaments used for weft are of secondary cellulose acetate 150 denierwith 32fibrils. The number of filaments in the warp is 72/cm. and in theweft 30/cm.

This woven fabric is treated as described in Example 1 with theexception that the embossing is carried out with a medium crystalpattern at a temperature of 130 C. and a pressure of 7 tons for acalendering machine with a width of 100 cm. The obtained woven fabrichas excellent touch and gives crease resistance and is especially suitedfor tailored dresses.

EXAMPLE 3 Woven fabric is used wherein the warp threads are of secondarycellulose acetate of 75 denier with 50 individual fibrils. The weftthreads are also of secondary cellulose acetate of 150 denier with 100individual fibrils. The number of threads in the warp is 73/cm. and inthe weft 30/cm.

The fabric is treated by embossing a finely crystalline pattern on oneside with a 200 cm. working width at 10 tons pressure and 125 C.temperature. The so embossed fabric is Washed and desized in the usualmanner and then contacted under slack conditions with hot air at 190 to195 C. for 20 seconds. The fabric is then dyed with conventionaldyestuffs being careful not to stretch or crease during the dyeingoperation. After the dyeing, the fabric is rinsed and dried. The fabricis then contacted with dry steam at C. for 3 minutes while in a slackcondition.

The appearance and properties of the thus treated fabric, particularlyits crease resistance, are excellent.

EXAMPLE 4 Woven fabric is used having Warp threads of 100 denier with 24individual fibrils having irregular titre and weft threads of 150 denierwith 32 individual fibrils of an irregular titre. The number of warpthreads is 38/cm. and weft 28/ cm. The fabric is treated as in Example 3except that embossing is conducted on a 150 cm. working width machine atC. and an elevated pressure of 8 tons and the hot air treatment is at180 C. for 25 seconds. The resulting fabric shows excellent wash andwear properties.

EXAMPLE 5 The web is a knitted fabric (material derived from a warp loomin the sequence of L 1-0-4-5, L 1-001) which consists of yarns ofsecondary cellulose acetate. It is washed for 30 minutes at atemperature of 40 C. on a winch vat with a synthetic detergent (2 g./l.of water) for the sake of preliminary cleaning. Thereafter, the web iscarefully rinsed, the liquid drawn otf and the knitted fabric then driedon a frame under slack condition and by setting the width given by theframe measurements. The washed fabric is then embossed on one side witha fine grain pattern at a pressure of 9 tons in a cm. working widthmachine at 120 C. The embossed knitted fabric is then fixed on thepinstenter under free shrink conditions at a temperature of to C. for 25to 30 seconds. The fabric is then printed with dispersed dyestuffs byscreen printing process, thereafter dried, steamed by star steamerduring 30 minutes at 1 at pressure, carefully rinsed, moderately soaped,again rinsed, liquid drawn off and dried. The knitted web is thenbrightened (revived) with washfast products and then dried on a frameunder slack condition and by setting the given width. Finally, theknitted web is fixed for 4 minutes with steam as dry as possible at 120C. in a finish decatizing machine.

The same treatment may be applied to plain knitted fabrics. The fabrichas excellent wash and wear properties.

EXAMPLE 6 The web is a knitted fabric which consists of yarns ofsecondary cellulose acetate. This knitted fabric is treated as describedin Example 5 with the exception that after a preliminary cleaning, a oneside embossing is carried out at a temperature of 130 C. and a pressureof 8 tons for a calendering machine with a width of 150 cm. The hot airtreatment is conducted at a temperature of 185-190 C. for a period of 25seconds. The obtained knitted fabric has excellent touch and very goodcrease resistance.

EXAMPLE 7 The fabric of Example 5 is processed in the same manner asExample 5 except that the knitted fabric is not embossed. The obtainedfabric receives excellent touch and crease resistance properties.

EXAMPLE 8 Woven twill fabric was embossed on one side with a mediumcrystal pattern at a pressure of 7 tons, a temperature of 120 to 125 C.on a 100 cm. working width machine. The embossed fabric was desized at atemperature of 80 C., rinsed, the water removed by vacuum and dried at atemperature of 90 C.

The fabric was treated at 185 C. with hot air for 20 seconds in a slackcondition. The fabric was then dyed and finally treated with dry steamfor 4 minutes at 125 C.

It is understood that the above described illustrations and embodimentsare set forth for the purpose of describingthis invention and are notintended to limit its scope which is determined by the appended claims.

The wash and wear fabric produced according to the present invention isunique and has properties unobtainable by other known processes. Thedimensional stability and wrinklefree characteristics are superior.While the exact nature of the physical changes in the fabric are notclear it has been established that certain physical characteristics arechanged by the process according to the invention.

For example, when filaments of the same titre and length are compared,each of the same secondary cellulose acetate, one treated according tothe present invention and one not, the differences in solubility arereadily apparent.

' For example, a comparison of solubility in freshly distilled cinnamicaldehyde at 55 C. shows that filaments treated by the present inventionrequire over two times as long to dissolve and in many cases well overthree times as long. Furthermore, when comparing the swelling values oftreated and untreated secondary cellulose acetate fibers, it is seenthat the swelling capacity of the treated fibers is reduced by about 30percent as compared with the untreated fabric.

It is therefore clear that the process of the present invention producescertain physical changes in the fabric which seem to account for thesuperior wash and wear properties obtained by the present invention.

What we claim is:

1. A process for finishing secondary cellulose acetate woven fabrics toimpart to the fabric the ability to be reused after washing and dryingwithout ironing, said process comprising:

(a) embossing the fabric in esesentially a dry condition on at least oneside at an elevated pressure and at a temperature of from about 80 to150 C. to impart a pattern to the fabric whereby the thread issetabilized,

(b) washing and drying,

() dry heating the embossed fabric is essentially a dry condition at atemperature of between about 180 to 200 C. for from about 20 to 30seconds,

(d) coloring and drying the colored fabric,

(e) steam fixing the embossed and dry heated fabric in essentially a drycondition for from about 3 to 5 minutes at a temperautre of from about115 to 125 C., all steps in said process being under conditions whereinthe fabric is not stretched.

2. A process for finishing secondary cellulose acetate knitted fabricsto impart to the fabric the ability to be reused after washing anddrying without ironing, said process comprising:

(a) washing and drying,

(b) dry heating the fabric in an essentially dry condition at atemperautre of between about 180 to 200 C. for from about 20 to 30seconds,

(0) coloring and drying the colored fabric,

(d) steam fixing the dry heated fabric in essentially a dry conditionfor from about 3 to 5 minutes at a temperature from about 115 to 125 C.,all steps in said process being conducted under conditions wherein thefabric is not stretched.

3. A process according to claim 2 wherein the fabric is embossed on atleast one side at an elevated pressure and at a temperature of fromabout 80 to 150 C. to impart a pattern to the fabric whereby the threadis stabilized prior to dry heating.

4. A process according to claim 1 wherein the fabric is embossed withembossing rolls at an elevated pressure which linearly increases with anincrease in the working width of the embossing rolls and is equivalentto about 5 to 12 tons at a working width of to 200 cm.

5. A process according to claim 3 wherein the fabric is embossed withembossing rolls at an elevated pressure which linearly increases with anincrease in the working width of the embossing rolls and is equivalentto about 5 to 12 tons at a working width of 100 to 200 cm.

6. The process according to claim 1 comprising the steps of (a)embossing said fabric with embossing rolls on at least one side at anelevated pressure which linearly increases with an increase in theworking width of the embossing rolls and is equivalent to about 7 to 11tons at a working width of 100 to 200 cm. and a temperautre of fromabout to 130 C.,

(b) washing, desizing and drying,

(c) dry heating at a temperautre of between about 180 to 190 C. for fromabout 20 to 30 seconds,

(d) coloring the fabric, and

(e) steam fixing for from about 3 to 5 minutes at a temperautre ofbetween about 115 and C.

7. The process according to claim 1 wherein prior to step (a) the fabricis embossed with embossing rolls on at least one side at an elevatedpressure which linearly increases with an increase in the working widthof the embossing rolls and is equivalent to about 7 to 11 tons at aWorking width of 100 to 200 cm. and at a temperautre of from about 120to C.

8. The process according to claim 1 wherein the fabric after washing anddrying, is colored and dried prior to dry heating.

9. The process according to claim 1 wherein embossing is conducted at atemperature of between 120 and 130 C.

10. The process according to claim 3 wherein the embossing is conductedat a emperature of between about 120 to 130 C.

11. The process according to claim 1 wherein the dry heating of theembossed fabric is conducted at a temperature of between to C.

12. The process according to claim 2 wherein the dry heating of theembossed fabric is conducted at a temperature of between 180 to 190 C.

13. The process according to claim 2 comprising:

(a) washing,

(b) dry heating at a tempearutre of between about 180 to 190 C. for fromabout 20 to 30 seconds,

(c) coloring the fabric, and

(d) steam fixing for from about 3 to 5 minutes at a temperature ofbetween about 115 to 125 C.

14. The secondary cellulose acetate fabric produced by the process ofclaim 4.

15. The secondary cellulose acetate fabric produced by the process ofclaim 2.

References Cited UNITED STATES PATENTS 4/1948 Redman 26-l8.5 2/ 1967Davis et al. 28-76 po-mso Patent No.

Dated June 3, 1969 lnv Eugen Hasselkuss et al It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 2, line Column 2, line Column 2, line Column line Column lineColumn 5, line Column 7, line Column 7, line Column 7, line Column 7,line Column 7, line Column 8, line Column 8, line Column 8, line Column8, line Column 8, line (SEAL) Attest:

Edward M. Fletcher, Ir. Attasting Officer change "prefered" to preferredchange "corification" to cornification change "celluose" to cellulosechange "etetching" to stretching change Fabrils" to Fibrils change"streamer" to steamer change "esesentiall to essentially change"setabilized to stabilized change "is" to in change "temperautre" totemperature after "temperature" insert of change "temperautre" totemperature change "temperautre" to temperature change "temperautre" totemperature change "temperautre" to temperature change "tempearutre" totemperature SIGNED 'A'ND SEALED MAY 5 WIILIAM E. 80m, JR- Gonmissionar0! Rants

